Aqueous metal treatment composition

ABSTRACT

An aqueous metal surface treatment composition that includes (A) an aqueous dispersion of a phenolic novolak resin that includes water and a reaction product of a phenolic resin precursor, a modifying agent and a multi-hydroxy phenolic compound wherein the modifying agent includes at least one functional moiety that enables the modifying agent to react with the phenolic resin precursor and at least one ionic moiety, (B) an acid and, optionally, (C) a flexibilizer. According to one embodiment the modifying agent is an aromatic compound. According to another embodiment the ionic moiety of the modifying agent is sulfate, sulfonate, sulfinate, sulfenate or oxysulfonate and the dispersed phenolic resin reaction product has a carbon/sulfur atom ratio of 20:1 to 200:1.

This application claims benefit of U.S. Provisional Application No.60/072,782, filed Jan. 27, 1998.

BACKGROUND OF THE INVENTION

The present invention relates to an aqueous autodepositable compositionthat is useful as a metal surface treatment.

It is well-known that metal surfaces are subject to corrosive andchemical degradation. This degradation has been combated by theapplication of various treatments to the metal surface. Conversioncoating of the metal sur face is one such treatment. Conversion coatinggenerally involves treating the surface with chemicals that form a metalphosphate and/or metal oxide conversion coating on the metal surface.The conversion coating provides protection against corrosion and canenhance adhesion of any subsequent coatings. Phosphatizing is awell-established conversion process. However, phosphatizing suffers fromseveral drawbacks. It is a complex multistep process that is capitalintensive, requires close monitoring and can generate significantamounts of waste sludge. In addition, phosphatizing requires oxidativeaccelerators that promote corrosion and thus must be removed by multiplerinsing steps. Conventional inorganic phosphate conversion coatings arealso very brittle and thus can fracture. A seal coat also is typicallyapplied for good corrosion resistance that often includes hexavalentchrome which presents considerable environmental problems.

It is also generally known that the corrosion resistance or metalsubstrates can be improved by coating the substrate with anautodeposition composition that generally comprise an aqueous solutionof an acid, an oxidizing agent and a dispersed resin. Immersion of ametallic surface in an autodeposition composition produces what is saidto be a self-limiting protective coating on a metal substrate. Thegeneral principles and advantages of autodeposition are explained in amultitude of patents assigned to Parker Amchem and/or Henkel (see, forexample, U.S. Pat. Nos. 4,414,350; 4,994,521; 5,427,863; 5,061,523 and5,500,460).

U.S. Pat. No. 5,691,048 includes phosphoric acid in a list for possibleacids in an autodepositing composition, but hydrofluoric acid is thepreferred acid. This patent also lists hydrogen peroxide, chromic acid,potassium dichromate, nitric acid, sodium nitrate, sodium persulfate,ammonium persulfate, sodium perborate and ferric fluoride as possibleoxidizing agents. Hydrogen peroxide and ferric fluoride are preferred.

Phosphatizing is also a well-known conversion treatment for providingcorrosion resistance to metal surfaces. U.S. Pat. No. 5,011,551 relatesto a metal conversion coating composition that includes an aliphaticalcohol, phosphoric acid, an alkali nitrate, tannic acid and zincnitrate. U.S. Pat. No. 4,293,349 relates to a steel surface protectivecoating composition that includes pyrogallic acid glucoside, phosphoricacid, phosphates of bivalent transition metals such as Zn or Mn, Zn orMn nitrate, and, optionally, formaldehyde.

An environmentally acceptable, user-friendly metal treatment withsuperior corrosion resistance and fracture toughness would be verydesirable.

SUMMARY OF THE INVENTION

According to the present invention there is provided an aqueous metalsurface treatment composition that includes (A) an aqueous dispersion ofa phenolic novolak resin that includes water and a reaction product of aphenolic resin precursor, a modifying agent and a multi-hydroxy phenoliccompound wherein the modifying agent includes at least one functionalmoiety that enables the modifying agent to react with the phenolic resinprecursor and at least one ionic moiety, (B) an acid and, optionally,(C) a flexibilizer. According to one embodiment the modifying agent isail aromatic compound. According to another embodiment the ionic moietyof the modifying agent is sulfate, sulfonate, sulfinate, sulfenate oroxysulfonate and the dispersed phenolic resin reaction product has acarbon/sulfur atom ratio of 20:1 to 200:1.

The metal treatment composition preferably is applied toelectrochemically active metals such as steel. This treatment improvesadhesion of subsequent coatings such as primers and adhesives to themetal surface and it improves corrosion resistance. Since this treatmentrequires only a minimum number of coatings—typically less than three andoften only a single coating—it is much more user friendly thanconventional phosphatizing and eliminates the need for a seal coat. Inaddition, the metal treatment generally does not require any rinsingsteps subsequent to application of the metal treatment composition. Aunique feature of the invention is that the metal treatment compositionis autodepositable.

It has also been discovered that metal substrates treated with thecompositions of this invention may require sitting at ambient conditions(approximately 25° C.) for an extended time period after autodepositingand drying (approximately 2 to 24 hours after drying) and prior toapplication of a subsequent coating of a different composition. Thisintermediate time period is referred to herein as the “ambient stagingperiod”. Without this ambient staging period the corrosion resistance ofthe final product was inconsistent for certain demanding commercialapplications. In addition, formation of a uniformly thick metaltreatment coating is required for superior corrosion resistance. Toothin or too thick a coating also can be detrimental to corrosionprotection.

Addition of a control agent to autodeposition compositions has beenfound to dramatically improve uniform coating formation on more complexsurface topography and enhance the autodeposition ofsubsequently-applied compositions thus improving corrosion resistanceand overall robustness. The protective coating formed by the compositionof the invention is particularly useful for providing corrosionresistance to metal substrates that are subjected to significantstresses and/or strains causing significant flexing or movement of thesubstrate surface. Due to the improved deposition caused by the controlagent, the concentration of active ingredients in an autodepositablecomposition that includes the control agent can be reduced. Anotheradvantage of the invention is that there is no need to post-rinse thetreated surface in order to remove only control agent residue.Furthermore, the control agent eliminates or substantially eliminatesthe ambient staging period thus improving process efficiency.

Accordingly, a further embodiment of the invention provides an aqueousautodeposition composition that includes an autodepositable componentand a control agent, preferably an organic nitro material. Theautodepositable component preferably is an aqueous phenolic resindispersion, particularly the aqueous novolak dispersion mentioned above.The autodeposition composition is particularly useful as a metaltreatment composition that also includes an acid, especially phosphoricacid.

According to another embodiment of the invention there is provided amethod for treating a metal surface that includes applying to thesurface an aqueous autodeposition composition that includes anautodepositable component and the control agent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Unless otherwise indicated, description of components in chemicalnomenclature refers to the components at the time of addition to anycombination specified in the description, but does not necessarilypreclude chemical interactions among the components of a mixture oncemixed.

Certain terms used in this document are defined below.

“Primer” means a liquid composition applied to a surface as an undercoatbeneath a subsequently-applied covercoat. The covercoat can be anadhesive and the primer/adhesive covercoat forms an adhesive system forbonding tab two substrates together.

“Coating” means a liquid composition applied to a surface to form aprotective and/or aesthetically pleasing coating on the surface.

“Phenolic compound” means a compound that includes at least one hydroxyfunctional group attached to a carbon atom of an aromatic ring.Illustrative phenolic compounds include unsubstituted phenol per se,substituted phenols such as alkylated phenols and multi-hydroxy phenols,and hydroxy-substituted multi-ring aromatics. Illustrative alkylatedphenols include methylphenol (also known as cresol), dimethylphenol(also known as xylenol), 2-ethylphenol, pentylphenol and tert-butylphenol. “Multi-hydroxy phenolic compound” means a compound that includesmore than one hydroxy group on each aromatic ring. Illustrativemulti-hydroxy phenols include 1,3-benzenediol (also known asresorcinol), 1,2-benzenediol (also known as pyrocatechol),1,4-benzenediol (also known as hydroquinone), 1,2,3-benzenetriol (alsoknown as pyrogallol), 1,3,5-benzenetriol and4-tert-butyl-1,2-benzenediol (also known as tort-butyl catechol).Illustrative hydroxy-substituted multi-ring aromatics include4,4′-isopropylidenebisphenol (also known as bisphenol A),4,4′methylidenebisphenol (also known as bisphenol F) and naphthol.

“Aldehyde compound” means a compound having the generic formula RCHO.Illustrative aldehyde compounds include formaldehyde, acetaldehyde,propionaldehyde, n-butylaldehyde, n-valeraldehyde, caproaldehyde,heptaldehyde and other straight-chain aldehydes having up to 8 carbonatoms, as well as compounds that decompose to formaldehyde such asparaformaldehyde, trioxane, furfural, hexamethylenetriamine, acetalsthat liberate formaldehyde on heating, and benzaldehyde.

“Phenolic resin” generally means the reaction product of a phenoliccompound with an aldehyde compound. The molar ratio of the aldehydecompound (for example, formaldehyde) reacted with the phenolic compoundis referred to herein as the “F/P ratio”. The F/P ratio is calculated ona per hydroxy-substituted aromatic ring basis.

“Phenolic resin precursor” means an unmodified or conventional phenolicresin that is reacted with the aromatic modifying agent to produce thephenolic resin that is dispersed in an aqueous phase.

“Electrochemically active metals” means iron and all metals and alloysmore active than hydrogen in the electromotive series. Examples ofelectrochemically active metal surfaces include zinc, iron, aluminum andcold-rolled, polished, pickled, hot-rolled and galvanized steel.

“Ferrous” means iron and alloys of iron.

While not wising to be bound to any particular theory, it is believedthat the metal treatment of this invention is based on the principle ofautodeposition. When the treatment composition is applied to anelectrochemically active metal the acid reacts with the metal to formmultivalent ions (for example, ferric and/or ferrous ions in the case ofsteel) that appear to cause the treatment composition to deposit on themetal surface a self-limiting, substantially uniform, gelatinous, highlyacidic wet film. As the film dries (the drying can be accelerated byheating) the remaining phosphoric acid converts the surface to therespective metal compound with the respective negative ion of the acid(for example, metal phosphate in the case of phosphoric acid) forming aninterpenetrating network with chelating groups of the aqueous dispersedphenolic novolak resin (A). The coating that is formed when thecomposition is in contact with the metal surface is known as the“unconverted” state. The subsequent drying of the coating converts thecoating to a “converted” state. The formation of the coating issubstantially “self-limiting” in that the coating increases in thicknessand areal density (mass per unit area) the longer the time the metallicsubstrate is immersed in the metal treatment composition. The rate ofthickness and areal density increase, however, decreases rapidly wishimmersion time.

The autodeposition characteristic of the invention is important toprovide corrosion resistance. It allows for the formation of anexceptionally uniform film. Excellent corrosion resistance is possibleonly if the entire surface of a metal part is protected with a barriercoating. This requirement is usually difficult to achieve on substratesurfaces that have very complex topology. With the superiorautodeposition of this invention, wetting and thus protection of suchcomplex surfaces is achieved. A further advantage of the metal treatmentis that it can activate a metal surface for autodeposition of asubsequently applied coating or primer that includes a dispersedphenolic resin as described above. Such a primer is described in moredetail in commonly-owned U.S. Provisional Patent Application 60/072,779titled “Aqueous Primer or Coating”, filed Jan. 27, 1998.

Another important advantage of the metal treatment composition is that abath of the composition does not appear to change in composition ascumulative metal surfaces are dipped in the bath over a period of time.It is believed that since the very hydrophilic phenolic resin dispersionimmobolizes or coagulates on the metal surface as a swollen wet gelrather than as a precipitate, the composition of the bath is the same asthe deposited wet gel and the bath is not depleted. In addition, itappears that there is substantially no build-up of ferrous/ferric ionsin the bath.

An important component of the metal treatment composition is the aqueousdispersed phenolic novolak resin (A). This resin is responsible for theautodeposition characteristic of the metal treatment composition. Thephenolic novolak resin dispersion (A) of the inventive composition canbe obtained by initially reacting or mixing a phenolic resin precursorand a modifying agent—theoretically via a condensation reaction betweenthe phenolic resin precursor and the modifying agent. It should berecognized that resole resins cannot be used in or formulated into themetal treatment composition due to the presence of the acid. Under theacidic conditions of the metal treatment resoles are unstable and canadvance quickly to gellation at which point the system cannot form afilm.

One functional moiety of the modifying agent provides the ionic pendantgroup that enables stable dispersion of the phenolic resin. Without theionic pendant group, the phenolic resin would be unable to maintain astable dispersion in water. Since the ionic pendant group provides forthe stability of the dispersion there is neo need, or at the most aminimal need, for surfactants. The presence of surfactants in an aqueouscomposition is a well-known hindrance to the composition's performance.

The other important functional moiety in the modifying agent enables themodifying agent to react with the phenolic resin precursor. Themodifying agent can contain more than one ionic pendant group and morethan one reaction-enabling moiety.

Incorporation of aromatic sulfonate functional moieties into thephenolic resin structure via condensation is the preferred method ofproviding the ionic pendant groups. Accordingly, one class of ionicmoieties are substituents on an aromatic ring that include a sulfur atomcovalently or ionically bonded to a carbon atom of the aromatic ring.Examples of covalently bound sulfur-containing substituents aresulfonate (—S(O)₂O⁻M⁺), sulfinate (—S(O)O⁻M⁺), sulfenate (—SO⁻M⁺) andoxysulfonate (—OS(O)₂O⁻M⁺), wherein M can be any monovalent ion such asNa, Li, K, or NR¹ ₃ (wherein R¹ is hydrogen or an alkyl). Anotherexample of a covalently bound substituent is sulfate ion. Sulfonate isthe preferred ionic group. The modifying agent should not include orintroduce any multivalent ions into the phenolic resin dispersion sinceit is expected that the presence or multivalent ions would cause thephenolic resin to precipitate rather than remain dispersed.

The reaction-enabling functional moiety of the modifying agent can beany functional group that provides a site on the modifying agent forundergoing condensation with a phenolic resin. If tile phenolic resinprecursor is a resole, the modifying agent reacts with an alkylol orbenzyl ether group of the resole. If the modifying agent is aromatic,the reaction-enabling functional moiety is a substituent on the aromaticring that causes a site on the ring to be reactive to the alkylol orbenzyl ether of the resole precursor. An example of such a substituentis a hydroxy or hydroxyalkyl, with hydroxy being preferred. The hydroxy-or hydroxyalkyl-substituted aromatic modifying agent is reactive at asite ortho and/or para to each hydroxy or hydroxyalkyl substituent. Inother words, the aromatic modifying agent is bonded to, or incorporatedinto, the phenolic resin precursor at sites on the aromatic ring of themodifying agent that are ortho and/or para to a hydroxy or hydroxyalkylsubstituent. At least two reaction-enabling functional moieties arepreferred to enhance the reactivity of the aromatic modifying agent withthe phenolic resin precursor.

Alternatively, the reaction-enabling functional moiety of the modifyingagent can be a formyl group (—CHO), preferably attached to a carbon atomof an aromatic ring. In this instance, the phenolic resin precursor is anovolak rather than a resole. The novolak precursor is reacted via anacid catalyzed aldehyde condensation reaction with the formylgroup-containing modifying agent so that the formyl group forms adivalent methylene linkage to an active site on an aromatic ring of thebackbone structure of the novolak precursor. Consequently, the modifyingagent structure (including the ionic moiety) is incorporated into thephenolic structure through the generated methylene linkage. Examples ofsuch formyl group-containing modifying agents include 2-formylbenzenesulfonate, 5-formylfuran sulfonate and (R)(SO₃)CH—CH₂—C(O)(H) compoundswherein R is C₁-C₄ alkyl groups.

Another alternative reaction-enabling functional moiety could be a diazogroup (—N₂ ⁺), preferably attached to a carbon atom of an aromatic ring.In this instance, the phenolic resin precursor is a novolak rather thana resole. The novolak precursor is reacted via a diazo coupling reactionwith the diazo group-containing modifying agent so that the diazo groupforms a divalent diazo linkage (—N═) to an active site on an aromaticring of the backbone structure of the novolak precursor. Consequently,the modifying agent structure (including the ionic moiety) isincorporated into the phenolic structure through the diazo linkage. Anexample of such diazo modifying agents is 1-diazo-2-naphthol-4-sulfonicacid.

The modifying agent also can optionally include a functional moiety thatis capable of chelating with a metal ion that is present on a substratesurface on which the phenolic resin dispersion is applied. The chelatinggroup remains as a residual group after the condensation of the phenolicresin precursor and the aromatic modifying agent. Typically, thechelating group is a substituent on the aromatic ring that is capable offorming a 5- or 6-membered chelation structure with a metal ion.Examples of such substituents include hydroxy and hydroxyalkyl, withhydroxy being preferred. At least two such functional groups must bepresent on the modifying agent molecule to provide the chelating. In thecase of an aromatic modifying agent, the chelating groups should belocated in an ortho position relative to each other. A significantadvantage of the invention is that hydroxy or hydroxyalkyl substituentson the aromatic modifying agent can serve two roles—condensationenablement and subsequent metal chelating.

An aromatic modifying agent is particularly advantageous. Preferably,the ionic group and the reaction-enabling moiety are not substituents onthe same aromatic ring. The ionic group, particularly sulfonate, appearsto have a strong deactivating effect on condensation reactions of thering to which it is attached. Consequently, an ionic group attached tothe same ring as the reaction-enabling moiety would not allow themodifying agent to readily react with the phenolic resin. However, itshould be recognized that this consideration for the location of theionic and reaction-enabling moieties is not applicable to the formylgroup-containing modifying agent and diazo modifying agent.

A preferred structure for the aromatic modifying agent is represented byformulae Ia or Ib below:

wherein X is the ionic group; Y is the reaction-enabling substituent: Zis the chelating substituent; L¹ is a divalent linking group such as analkylene radical (for example, methylene) or a diazo (—N═N—); a is 1; bis 1 to 4; m is 0 or 1; and c and d are each independently 0 to 3,provided there are not more than 4 substituents on each aromatic ring.If a chelating group Z is present it is positioned ortho to anotherchelating group Z or to Y. It should be recognized that thereaction-enabling substituent Y may also act as a chelating substituent.In this instance, the aromatic modifying agent may not include anindependent chelating substituent Z. An aromatic modifying agentaccording to formulae Ia or Ib could also include other substituentsprovided they do not adversely interfere with the ionic group or thecondensation reaction.

Illustrative aromatic modifying agents include salts of6,7-dihydroxy-2-naphthalenesulfonate;6,7-dihydroxy-1-naphthalenesulfonate;6,7-dihydroxy-4-naphthalenesulfonate; Acid Red 88; Acid Alizarin VioletN; Erichrome Black T; Erichrome Blue Black B; Brilliant Yellow; CroceinOrange G; Biebrich Yellow; and Palatine Chrome Black 6BN.6,7-dihydroxy-2-naphthalenesulfonate, sodium salt is the preferredaromatic modifying agent.

It should be recognized that the preferred sulfonate modificationcontemplated herein involves an indirect sulfonation mechanism. In otherwords, the aromatic modifying agent includes a sulfonate group and isreacted with another aromatic compound (the phenolic resin precursor) toobtain the chain extended, sulfonate-modified phenolic resin product.This indirect sulfonation is distinctly different than directsulfonation of the phenolic resin precursor.

Any phenolic resin could be employed as the phenolic resin precursor,but it has been found that resoles are especially suitable. The resoleprecursor should have a sufficient amount of active alkylol or benzylether groups that can initially condense with the modifying agent andthen undergo further subsequent condensation. Of course, the phenolicresin precursor has a lower molecular weight than the final dispersedresin since a the precursor undergoes condensation to make the finaldispersed resin. Resoles are prepared by reacting a phenolic compoundwith an excess of an aldehyde in the presence of a base catalyst. Resoleresins are usually supplied and used as reaction product mixtures ofmonomeric phenolic compounds and higher molecular weight condensationproducts having alkylol (—ArCH—OH) or benzyl ether termination(—ArCH₂—O—CH₂Ar), wherein Ar is an aryl group. These resole mixtures orprepolymers (also known as stage A resin) can be transformed intothree-dimensional, crosslinked, insoluble and infusible polymers by theapplication of heat.

The reactants, conditions and catalysts for preparing resoles suitablefor the resole precursor of the present invention are well-known. Thephenolic compound can be any of those previously listed or other similarcompounds, although multi-hydroxy phenolic compounds are undesirable.Particularly preferred phenolic compounds for making the resoleprecursor include phenol per se and alkylated phenol. The aldehyde alsocan be any of those previously listed or other similar compounds, withformaldehyde being preferred. Low molecular weight, water soluble orpartially water soluble resoles are preferred as the precursor becausesuch resoles maximize the ability to condense with the modifying agent.The F/P ratio of the resole precursor'should be at least 0.90.Illustrative commercially available resoles that are suitable for use asa precursor include a partially water soluble resole available fromGeorgia Pacific under the trade designation BRL 2741 and a partiallywater soluble resoles available from Schenectady International under thetrade designations HRJ11722 and SG3100.

Preferably, the dispersed novolak is produced by reacting or mixing 1mol of modifying agent(s) with 2-20 mol of phenolic resin (preferablyresole) precursor(s) and, preferably, 2-20 mol of multi-hydroxy phenoliccompound(s). An aldehyde compound, preferably formaldehyde, is alsorequired to make the novolak. The aldehyde compound can optionally beadded as a separate ingredient in the initial reaction mixture or thealdehyde compound can be generated in situ from the resole precursor.The resole precursor(s), multi-hydroxy phenolic compound(s) andmodifying agent(s) co-condense to form the dispersed novolak. Thereaction typically is acid catalyzed with an acid such as phosphoricacid. The F/P ratio of aldehyde compound(s) to combined amount of resoleprecursor(s) and multi-hydroxy phenolic compound(s) in the initialreaction mixture preferably is less than 0.9. Preferably, synthesis ofthe dispersed novolak is a two stage reaction. In the first stage, theresole precursor(s) is reacted with the modifying agent(s) and,optionally, a small amount of multi-hydroxy phenolic compound(s). Oncethis first stage reaction has reached the desired point (i.e. the resincan be readily formed into a translucent dispersion), the acid catalystand a greater amount of multi-hydroxy phenolic compound(s) is added tothe reaction mixture. Pyrocatechol (also simply known as catechol) is apreferred multi-hydroxy phenolic compound for reacting in the firststage and resorcinol is a preferred multi-hydroxy phenolic compound forreacting in the second stage.

Hydrophilic novolaks typically have a hydroxy equivalents of between 1and 3 per aromatic ring. Preferably, dispersed hydrophilic novolaksaccording to the invention have a hydroxy equivalents of 1.1 to 2.5,more preferably 1.1 to 2.0. The hydroxy equivalents is calculated basedon the amount of multi-hydroxy phenolic compounds used to make thenovolak.

According to a preferred embodiment, the dispersed phenolic resinreaction product contains a mixture of oligomers having structuresbelieved to be represented by the following formulae Ia or IIb:

wherein X, Y, Z and L¹ and subscripts a, b, c, d and m are the same asin formulae Ia and Ib, e is 1 to 6, L² is a divalent linking group andPh is the phenolic resin backbone structure, provided the -(L² -Ph)group(s) is(are) ortho or para to a Y group. L1 depends upon theparticular phenolic resin, but typically is a divalent alkylene radicalsuch as methylene (—CH₂—) or oxydimethylene (—CH₂—O—CH₂—). Preferably. cis 2 and the -(L²-Ph) groups are in para position to each other.

According to a preferred embodiment wherein the phenolic resin is anovolak and the modifying agent is a naphthalene having a ionic pendantgroup X and two reaction-enabling substituents Y, the dispersed phenolicresin reaction product contains a mixture of oligomers having structuresbelieved to be represented by the following formula IV:

wherein X and Y are the same as in formulae Ia and Ib, a is 0 or 1, n is0 to 5 and R⁴ is independently hydroxyl, alkyl, aryl, alkylaryl or arylether. Preferably, R⁴ is tert-butyl. If6,7-dihydroxy-2-naphthalenesulfonate, sodium salt is the modifyingagent, X will be SO₃ ⁻Na⁺ and each Y will be OH. In this case thehydroxy groups for Y will also act as chelating groups with a metal ion.

It should be recognized that the dispersed phenolic resin reactionproduct may also contain oligomers or compounds having structures thatvary from the idealized structures shown in formula IV.

If the modifying agent includes a sulfur-containing ionic group, theresulting modified phenolic resin should have a carbon/sulfur atom ratioof 20:1 to 200:1, preferably 20:1 to 100:1. If the sulfur content isgreater than the 20:1 carbon/sulfur tom ratio, the modified phenolicresin begins to become water soluble, is more stable with respect tomultivalent ions and is difficult to thermoset. These characteristicsarc adverse to the preferred use of the phenolic resin dispersion of theinvention. If the sulfur content is below the 200:1 carbon/sulfur atomratio, then the resin dispersion cannot maintain its stability. Viewedanother way, the dispersed phenolic resins have 0.01 to 0.10, preferably0.03 to 0.06, equivalents of sulfonate functionality/100 g resin. Theaqueous dispersion of the phenolic resin preferably has a solids contentof 1 to 50, preferably 15 to 30.

The modifying agent and the phenolic resin precursor can be reactedunder conditions effective to promote condensation of the modifyingagent with the phenolic resin precursor. The reaction is carried out inwater under standard phenolic resin condensation techniques andconditions. The reactant mixture (including water) generally is heatedfrom 50 to 100° C. under ambient pressure, although the specifictemperature may differ considerably depending upon the specificreactants and the desired reaction product. The resulting product is aconcentrate that is self-dispersible upon the addition of water andagitation to reach a desired solids content. The final dispersion can befiltered to remove any gelled agglomerations.

The intermediate modified resoles or novolaks that are initiallyproduced in the synthesis are not necessarily water dispersible, but asthe chain extension is advanced the resulting chain extended modifiedresoles or novolaks become progressively more water dispersible bysimple mechanical agitation. The chain extension for the dispersedresole is determined by measuring the viscosity of the reaction mixture.Once the resole reaction mixture has a reached the desired viscosity,which varies depending upon the reactant composition, the reaction isstopped by removing the heat. The chain extension for the dispersednovolak is determined by pre-selecting the F/P ratio of the totalreaction mixture (in other words, the amount of aldehyde compound(s)relative to the amount of phenolic(s) in both the first and secondstages). The reaction for the, novolak is allowed to proceed untilsubstantially all the total amount of the reactants have reacted. Inother words, there is essentially no unreacted reactant remaining.Preferably, the molecular weight (i.e., chain extension) of the novolakshould be advanced to just below the gel point.

The novolak dispersion can be present in the metal treatment compositionin any amount. Preferably, it is present in an amount of 1 to 20, morepreferably, 2 to 6, weight percent based on the total weight of thenon-volatile components of the composition.

The phenolic resin dispersion forms environmentally (especiallycorrosion) resistant, non-resolvatable films when applied to a metalsurface and cured. As used herein, “non-resolvatable” means that thefilm does not resolvate when an aqueous covercoat is applied to the filmbefore it is thermoset. If the film resolvated, the components of thefilm would dissolve or disperse into the aqueous covercoat thusdestroying any advantage intended from the formation of the film on asurface. The low ionic content of the modified phenolic resin dispersion(relative to water soluble phenolic resins) allows them to behavesimilarly to non-ionically modified resins and form very water resistantfilms on curing.

The acid can be any acid that is capable of reacting with a metal togenerate multivalent ions. Illustrative acids include hydrofluoric acid,phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid. Inthe case of steel the multivalent ions will be ferric and/or ferrousions. Aqueous solutions of phosphoric acid are preferred. When the acidis mixed into the composition presumably the respective ions ate formedand exist as independent species in addition to the presence of the freeacid. In other words, in the case of phosphoric acid, phosphate ions andfree phosphoric acid co-exist in the formulated final multi-componentcomposition. The acid preferably is present in an amount of 5 to 300parts by weight, more preferably 10 to 1609 parts by weight, based on100 parts by weight of the phenolic novolak resin dispersion (A).

Water, preferably deionized water, is utilized in the metal treatmentcomposition of the invention in order to vary the solids content.Although the solids content may be varied as desired, the solids contentof the metal treatment composition typically is 1 to 10, preferably 3 to6%. Since the metal treatment composition is waterborne it issubstantially free of volatile organic compounds.

The resulting coating from application of the metal treatmentcomposition is a thin, tightly bound interpenetrating organic/inorganicmatrix of phenolic/metal phosphates at the metal substrate interface.This matrix can be further flexibilized with polymers. The flexibilizer(C) is any material that contributes flexibility and/or toughness to thefilm formed from the composition. The toughness provided by theflexibilizer provides fracture resistance to the film. The flexibilizershould be non-glassy at ambient temperature and be an aqueous emulsionlatex or aqueous dispersion that is compatible with the phenolic novolakresin dispersion (A). The flexibilizer preferably is formulated into thecomposition in the form or an aqueous emulsion latex or aqueousdispersion

Suitable flexibilizers include aqueous latices, emulsions or dispersionsof (poly)butadiene, neoprene, styrene-butadiene rubber,acrylonitrile-butadiene rubber (also known as nitrile rubber),halogenated polyolefin, acrylic polymer, urethane polymer,ethylene-propylene copolymer rubber, ethylene-propylene-diene terpolymerrubber, styrene-acrylic copolymer, polyamide, poly(vinyl acetate) andthe like. Halogenated polyolefins, nitrile rubbers and styrene-acryliccopolymers are preferred.

A suitable styrene-acrylic polymer latex is commercially available fromGoodyear Tire & Rubber under the trade designation PLIOTEC anddescribed, for example, in U.S. Pat. Nos. 4,968,741; 5,122,566 and5,616,635. According to U.S. Pat. No. 5,616,635, such a copolymer latexis made from 45-85 weight percent vinyl aromatic monomers, 15-50 weightpercent of at least one alkyl acrylate monomer and 1-6 weight percentunsaturated carbonyl compound. Styrene is the preferred vinyl aromaticmonomer, butyl acrylate is the preferred acrylate monomer and acrylicacid and methacrylic acid are the preferred unsaturated carbonylcompound. The mixture for making the latex also includes at least onephosphate ester surfactant, at least one water-insoluble nonionicsurface active agent and at least one free radical initiator.

If nitrile rubber is the flexibilizer, it is preferably mixed into thecomposition as an emulsion latex. It is known in the art that nitrilerubber emulsion latices are generally made from at least one monomer ofacrylonitrile or an alkyl derivative thereof and at least one monomer ofa conjugated diene, preferably butadiene. According to U.S. Pat. No.4,920,176 the acrylonitrile or alkyl derivative monomer should bepresent in an amount of 0 or 1 to 50 percent by weight based on thetotal weight of the monomers. The conjugated diene monomer should bepresent in an amount of 50 percent to 99 percent by weight based on thetotal weight of the monomers. The nitrile rubbers can also optionallyinclude various co-monomers such as acrylic acid or various estersthereof, dicarboxylic acids or combinations thereof. The polymerizationof the monomers typically is initiated via free radical catalysts.Anionic surfactants typically are also added. A suitable nitrile rubberlatex is available from B.F. Goodrich under the trade designation HYCAR.

Representative halogenated polyolefins include chlorinated naturalrubber, chlorine- and bromine-containing synthetic rubbers includingpolychloroprene, chlorinated polychloroprene, chlorinated polybutadiene,hexachloropentadiene, butadiene/halogenated cyclic conjugated dieneadducts, chlorinated butadiene styrene copolymers, chlorinated ethylenepropylene copolymers and ethylene/propylene/non-conjugated dieneterpolymers, chlorinated polyethylene, chlorosulfonated polyethylene,poly(2,3-dichloro-1,3-butadiene), brominatedpoly(2,3-dichloro-1,3-butadiene), copolymers of (α-haloacrylonitrilesand 2,3-dichloro-1,3-butadiene, chlorinated poly(vinyl chloride) and thelike including mixtures of such halogen-containing elastomers.

Latices of the halogenated polyolefin can be prepared according tomethods known in the art such as by dissolving the halogenatedpolyolefin in a solvent and adding a surfactant to the resultingsolution. Water can then be added to the solution under high shear toemulsify the polymer. The solvent is then stripped to obtain a latex.The latex can also be prepared by emulsion polymerization of thehalogenated ethylenically unsaturated monomers.

Butadiene latices are particularly preferred as the flexibilizer (C).Methods for making butadiene latices are well-known and are described,for example, in U.S. Pat. Nos. 4,054,547 and 3,920,600, bothincorporated herein by reference. In addition, U.S. Pat. Nos. 5,200,459;5,300,555; and 5,496,884 disclose emulsion polymerization of butadienemonomers in the presence of polyvinyl alcohol and a co-solvent such asan organic alcohol or a glycol.

The butadiene monomers useful for preparing the butadiene polymer latexcan essentially be any monomer containing conjugated unsaturation.Typical monomers include 2,3-dichloro-1,3-butadiene; 1,3-butadiene;2,3-dibromo-1,3-butadiene isoprene; isoprene; 2,3-dimethylbutadiene;chloroprene; bromoprene; 2,3-dibromo-1,3-butadiene;1,1,2-trichlorobutadiene; cyanoprene; hexachlorobutadiene; andcombinations thereof. It is particularly preferred to use2,3-dichloro-1,3-butadiene since a polymer that contains as its majorportion 2,3-dichloro-1,3-butadiene monomer units has born found to beparticularly useful in adhesive applications due to the excellentbonding ability and barrier properties of the2,3-dichloro-1,3-butadiene-based polymers. As described above, anespecially preferred embodiment of the present invention is one whereinthe butadiene polymer includes at least 60 weight percent, preferably atleast 70 w eight percent, 2,3-dichloro-1,3-butadiene monomer units.

The butadiene monomer can be copolymerized with other monomers. Suchcopolymerizable monomers include α-haloacrylonitriles such asα-bromoacrylonitrile and α-chloroacrylonitrile; α,β-unsaturatedcarboxylic acids such as acrylic, methacrylic, 2-ethylacrylic,2-propylacrylic, 2-butylacrylic and itaconic acids;alkyl-2-haloacrylates such as ethyl-2-chloroacrylate andethyl-2-bromoacrylate; α-bromovinylketone; vinylidene chloride; vinyltoluenes; vinylnaphthalenes; vinyl ethers, esters and ketones such asmethyl vinyl ether, vinyl acetate and methyl vinyl ketone; estersamides, and nitrites of acrylic and methacrylic acids such as ethylacrylate, methyl methacrylate, glycidyl acrylate, methacrylamide andacrylonitrile; and combinations of such monomers. The copolymerizablemonomers, if utilized, are preferably α-haloacrylonitrile and/orα,β-unsaturated carboxylic acids. The copolymerizable monomers may beutilized in an amount of 0.1 to 30 weight percent, based on the weightof the total monomers utilized to form the butadiene polymer.

In carrying out the emulsion polymerization to produce the latex otheroptional ingredients may be employed during the polymerization process.For example, conventional anionic and/or nonionic surfactants may beutilized in order to aid in the formation of the latex. Typical anionicsurfactants include carboxylates such as fatty acid soaps from lauric,stearic, and oleic acid; acyl derivatives of sarcosine such as methylglycine; sulfates such as sodium lauryl sulfate; sulfated natural oilsand esters such as Turkey Red Oil; alkyl aryl polyether sulfates; alkalialkyl sulfates; ethoxylated aryl sulfonic acid salts; alkyl arylpolyether sulfonates; isopropyl naphthalene sulfonates; sulfosuccinates;phosphate esters such as short chain fatty alcohol partial esters ofcomplex phosphates; and orthophosphate esters of polyethoxylated fattyalcohols. Typical nonionic surfactants include ethoxylated (ethyleneoxide) derivatives such as ethoxylated alkyl aryl derivatives; mono- andpolyhydric alcohols; ethylene oxide/propylene oxide block copolymers;esters such as glyceryl monostearate; products of the dehydration ofsorbitol such as sorbitan monostearate and polyethylene oxide sorbitanmonolaurate; amines; lauric acid; and isopropenyl halide. A conventionalsurfactant, if utilized, is employed in an amount of 0.01 to 5 parts,preferably 0.1 to 2 parts, per 100 parts by weight of total monomersutilized to form the butadiene polymer.

In the case of dichlorobutadiene homopolymers, anionic surfactants areparticularly useful. Such anionic surfactants include alkyl sultanatesand alkyl aryl sulfonates (commercially available from Stepan under thetrade designation POLYSTEP) and sulfonic acids or salts of alkylateddiphenyl oxide (for example, didodecyl diphenyleneoxide disulfonate ordihexyl diphenyloxide disulfonate commercially available from DowChemical Co. under the trade designation DOWFAX).

Chain transfer agents may also be employed during emulsionpolymerization in order to control the molecular weight of the butadienepolymer and to modify the physical properties of the resultant polymeras is known in the art. Any of the conventional organicsulfur-containing chain transfer agents may be utilized such as alkylmercaptans and dialkyl xanthogen disulfides.

The emulsion polymerization is typically triggered by a free radicalinitiator. Illustrative free radical initiators include conventionalredox systems, peroxide systems, azo derivatives and hydroperoxidesystems. The use of a redox system is preferred and examples of suchsystems include ammonium persulfate/sodium metabisulfite, ferricsulfate/ascorbic acid/hydroperoxide and tributylborane/hydroperoxide,with ammonium persulfate/sodium metabisulfite being most preferred.

The emulsion polymerization is typically carried out at a temperature of10°-90° C., preferably 40°-60° C. Monomer conversion usually ranges from70-100, preferably 80-100, percent. The latices preferably have a solidscontent of 10 to 70, more preferably 30 to 60, percent; a viscositybetween 50 and 10,000 centipoise at 25° C.; and a particle size between60 and 300 nanometers.

Especially preferred as the butadiene latex is a butadiene polymer thathas been emulsion polymerized in the presence of a styrene sulfonicacid, styrene sulfonate, poly(styrene sulfonic acid), or poly(styrenesulfonate) stabilizer to form the latex. Poly(styrene sulfonate) is thepreferred stabilizer. This stabilization system is particularlyeffective for a butadiene polymer that is derived from at least 60weight percent dichlorobutadiene monomer, based on the amount of totalmonomers used to form the butadiene polymer. The butadiene polymer latexcan be made by known emulsion polymerization techniques that involvepolymerizing the butadiene monomer (and copolymerizable monomer, ifpresent) in the presence of water and the styrene sulfonic acid, styrenesulfonate, poly(styrene sulfonic acid), or poly(styrene sulfonate)stabilizer. The sulfonates can be salts of any cationic groups such assodium, potassium or quaternary ammonium. Sodium styrene sulfonate is apreferred styrene sulfonate compound. Poly(styrene sulfonate) polymersinclude poly(styrene sulfonate) homopolymer and poly(styrene sulfonate)copolymers such as those with maleic anhydride. Sodium salts ofpoly(styrenic sulfonate) are particularly preferred and are commerciallyavailable from National Starch under the trade designation VERSA TL. Thepoly(styrene sulfonate) can have a weight average molecular weight from5×10⁴ to 1.5×10⁶, with 1.5×10⁵ to 2.5×10⁵ being preferred. In the caseof a poly(styrene sulfonate) or poly(styrene sulfonic acid) it isimportant to recognize that the emulsion polymerization takes place inthe presence of the pre-formed polymer. In other words, the butadienemonomer is contacted with the pre-formed poly(styrene sulfonate) orpoly(styrene sulfonic acid). The stabilizer preferably is present in anamount of 0.1 to 10 parts, preferably 1 to 5 parts, per 100 parts byweight of total monomers utilized to form the butadiene polymer.

The flexibilizer (C), if present, preferably is included in thecomposition in an amount of 5 parts by weight to 300 parts by weight,based on 100 parts by weight phenolic novolak resin dispersion (A). Morepreferably, the flexibilizer is present in an amount of 25 parts byweight to 100 parts by weight, based on 100 parts by weight of thephenolic novolak resin dispersion (A).

The modified phenolic resin dispersion can be cured to form a highlycrosslinked thermoset via known curing methods for phenolic resins. Thecuring mechanism can vary depending upon the use and form of thephenolic resin dispersion. For example, curing of the dispersed resoleembodiment typically can be accomplished by subjecting the phenolicresin dispersion to heat. Curing of the dispersed novolak embodimenttypically can be accomplished by addition of an aldehyde donor compound.

Since the dispersed phenolic resin (A) is a novolak, a curative shouldbe introduced in order to cure the film formed by the metal treatmentcomposition. It should be noted that the metal treatment compositioncannot itself include a phenolic resin curative these curatives are notstorage stable under acidic conditions. Curing of the film can beaccomplished by the application of a curative-containing topcoat overthe metal treatment film. Typically, the metal treatment composition isapplied to a metal surface (either conventionally or via autodeposition)and then dried. The curative-containing topcoat then is applied to thethus treated metal surface. The curative contained in the topcoat can bean aldehyde donor compound or an aromatic nitroso compound. Topcoatcompositions that include either one or both of these curatives arewell-known and commercially available.

The aldehyde donor can be essentially be any type of aldehyde known toreact with hydroxy aromatic compounds to form cured or crosslinkednovolak phenolic resins. Typical compounds useful as an aldehyde (e.g.,formaldehyde) source in the present invention include formaldehyde andaqueous solutions of formaldehyde, such as formalin; acetaldehyde;propionaldehyde; isobutyraldehyde; 2-ethyhexaldehyde;2-methylpentaldehyde; 2-ethyhexaldehyde; benzaldehyde; as well ascompounds which decompose to formaldehyde, such as paraformaldehyde,trioxane, furfural, hexamethylenetetramine, anhydromaldehydeaniline,ethylene diamine formaldehyde; acetals which liberate formaldehyde onheating; methylol derivatives of urea and formaldehyde; methylolphenolic compounds; and the like.

It has been found that when the metal treatment composition is used incombination with the primer described in U.S. Provisional PatentApplication No. 60/072,779 (incorporated herein by reference),formaldehyde species generated from the resole present in the primerappear to co-cure the novolak in the metal treatment coating viadiffusion. In addition, curing or crosslinking of the novolak may occurthrough ionic crosslinking and chelation with the metal ions generatedby the acid-metal substrate reaction.

Additionally, high molecular weight aldehyde homopolymers and copolymerscan be employed as a latent formaldehyde source in the practice of thepresent invention. A latent formaldehyde source herein refers to aformaldehyde source which will release formaldehyde only in the presenceof heat such as the heat applied during the curing of an adhesivesystem. Typical high molecular weight aldehyde homopolymers andcopolymers include (1) acetal homopolymers, (2) acetal copolymers, (3)gamma-polyoxy-methylene ethers having the characteristic structure:

R₁₀O—(CH₂O)_(n)—R₁₁

and (4) polyoxymethylene glycols having the characteristic structure:

HO—(R₁₂O)_(x)—(CH₂O)_(n)—(R₁₃O)_(k)—H

wherein R₁₀ and R₁₁ can be the same or different and each is an alkylgroup having from about 1 to 8, preferably 1 to 4, carbon atoms, R₁₂ andR₁₃ can be the same or different and each is an alkylene group havingfrom 2 to 12, preferably 2 to 8, carbon atoms; n is greater than 100,and is preferably in the range from about 200 to about 2000; and x is inthe range from about 0 to 8, preferably 1 to 4, with at least one xbeing equal to at least 1. The high molecular weight aldehydehomopolymers and copolymers are further characterized by a melting pointof at least 75° C., i.e. they are substantially inert with respect tothe phenolic system until heat activated; and by being substantiallycompletely insoluble in water at a temperature below the melting point.The acetal homopolymers and acetal copolymers are well-known articles ofcommerce. The polyoxymethylene materials are also well known and can bereadily synthesized by the reaction of monoalcohols having from 1 to 8carbon atoms or dihydroxy glycols and ether glycols withpolyoxymethylene glycols in the presence of an acidic catalyst. Arepresentative method of preparing these crosslinking agents isdescribed in U.S. Pat. No. 2,512,950, which is incorporated herein byreference. Gamma-polyoxymethylene ethers are generally preferred sourcesof latent formaldehyde and a particularly preferred latent formaldehydesource for use in the practice of the invention is 2-polyoxymethylenedimethyl ether.

The aromatic nitroso compound can be any aromatic hydrocarbon, such asbenzenes, naphthalenes, anthracenes, biphenyls, and the like, containingat least two nitroso groups attached directly to non-adjacent ringcarbon atoms. Such aromatic nitroso compounds are described, forexample, in U.S. Pat. No. 3,258,388; U.S. Pat. No. 4,119,587 and U.S.Pat. No. 5,496,884.

More particularly, such nitroso compounds are described as aromaticcompounds having from 1 to 3 aromatic nuclei, including fused aromaticnuclei, having from 2 to 6 nitroso groups attached directly tonon-adjacent nuclear carbon atoms. The preferred nitroso compounds arethe dinitroso aromatic compounds, especially the dinitrosobenzenes anddinitrosonaphthalenes, such as the meta- or para-dinitrosobenzenes andthe meta- or para-dinitrosonaphthalenes. The nuclear hydrogen atoms ofthe aromatic nucleus can be replaced by alkyl, alkoxy, cycloalkyl, aryl,aralkyl, alkaryl, arylamine, arylnitroso, amino, halogen and similargroups. Thus, where reference is made herein to “aromatic nitrosocompound” it will be understood to include both substituted andunsubstituted nitroso compounds.

Particularly preferred nitroso compounds are characterized by theformula:

(R)_(m)—Ar—(NO)₂

wherein Ar is selected from the group consisting of phenylene andnaphthalene; R is a monovalent organic radical selected from the groupconsisting of alkyl, cycloalkyl, aryl, aralkyl, alkaryl, arylamine andalkoxy radicals having from 1 to 20 carbon atoms, amino, or halogen, andis preferably an alkyl group having from 1 to 8 carbon atoms; and m is0; 1, 2, 3, or 4, and preferably is 0.

Exemplary suitable aromatic nitroso compounds includem-dinitrosobenzene, p-dinitrosobenzene, m-dinitrosonaphthalene,p-dinitrosonaphthalene, 2,5-dinitroso-p-cymene,2-methyl-1,4-dinitrosobenzene, 2-methyl-5-chloro-1,4-dinitrosobenzene,2-fluoro-1,4-dinitrosobenzene, 2-methoxy-1-3-dinitrosobenzene,5-chloro-1,3-dinitrosobenzene, 2-benzyl-1,4-dinitrosobenzene,2-cyclohexyl-1,4-dinitrosobenzene and combinations thereof. Particularlypreferred are m-dinitrosobenzene and p-dinitrosobenzene.

The aromatic nitroso compound precursor may be essentially any compoundthat is capable of being converted, typically by oxidation, to a nitrosocompound at elevated temperatures, typically from about 140-200° C. Themost common aromatic nitroso compound precursors are derivatives ofquinone compounds. Examples of such quinone compound derivatives includequinone dioxime, dibenzoquinone dioxime,1,2,4,5-tetrachlorobenzoquinone, 2-methyl-1,4-benzoquinone dioxime,1,4-naphthoquinone dioxime, 1,2-naphthoquinone dioxime and2,6-naphthoquinone dioxime.

The control agent mentioned above is especially useful in the metaltreatment composition of the invention described above but it could alsobe useful in any multi-component composition that includes anautodepositable component. The autodepositable component is any materialthat enables (either by itself or in combination with the othercomponents of the composition) the multi-component composition toautodeposit on a metal surface. Preferably, the autodepositablecomponent is any water-dispersible or water soluble resin that iscapable of providing autodeposition ability to the composition. Suchresins include those derived from ethylenically unsaturated monomerssuch as polyvinylidene chloride, polyvinyl chloride, polyethylene,acrylic, acrylonitrile, polyvinyl acetate and styrene-butadiene (seeU.S. Pat. Nos. 4,414,350; 4,994,521; and 5,427,863; and PCT PublishedPatent Application No. WO 93/15154). Urethane and polyester resins arealso mentioned as being useful. Certain epoxy and epoxy-acrylate resinsare also said to be useful autodeposition resins (see U.S. Pat. No.5,500,460 and PCT Published Patent Application No. WO 97/07163). Blendsof these resins may also be used.

Especially suitable autodepositable resins are aqueous phenolic resindispersions described in co-pending, commonly assigned U.S. ProvisionalPaten Application No. 60/072887, incorporated herein by reference. Thenovolak version of this dispersed resin is described above in connectionwith the metal treatment composition. There is also a resole versionwith which the control agent of the invention may be formulated into amulti-component composition.

The phenolic resin precursor and modifying agent used to make thedispersed resole are the same as those described for the dispersednovolak. However, the dispersed resole is produced by the reaction of 1mol of modifying agent(s) with 1 to 20 mol of phenolic resinprecursor(s). A dispersed resole typically can be obtained by reacting aresole precursor or a mixture of resole precursors with the modifyingagent or a mixture of agents without any other reactants, additives orcatalysts. However, other reactants, additives or catalysts can be usedas desired. Multi-hydroxy phenolic compound(s) can optionally beincluded in relatively small amounts in the reactant mixture for theresole. Synthesis of the resole does not require an acid catalyst.

Hydrophilic resoles typically have a F/P ratio of at least 1.0.According to the invention, hydrophilic resoles having a F/P ratio muchgreater than 1.0 can be successfully dispersed. For example, it ispossible to make an aqueous dispersion of hydrophilic resoles having aF/P ratio of at least 2 and approaching 3, which is the theoretical F/Pratio limit.

According to a particularly preferred embodiment wherein the dispersedphenolic resin is a resole and the modifying agent is a naphthalenehaving a ionic pendant group X and two reaction-enabling substituents Y,the dispersed phenolic resin reaction product contains a mixture ofoligomers having structures believed to be represented by the followingformula III:

wherein X and Y are the same as in formulae Ia and Ib, a is 0 or 1; n is0 to 5; R² is independently —C(R⁵)₂—or —C(R⁵)₂—O—C(R⁵)₂—, wherein R⁵ isindependently hydrogen, alkylol, hydroxyl, alkyl, aryl or aryl ether;and R³ is independently alkylol, alkyl, aryl or aryl ether. Preferably,R² is methylene or oxydimethylene and R³ is methylol. If6,7-dihydroxy-2-naphthalenesulfonate, sodium salt is the modifyingagent, X will be SO₃ ⁻Na⁺ and each Y will be OH. It should be recognizedthat in this case the hydroxy groups for Y will also act as chelatinggroups with a metal ion.

The autodepositable component can be present in the composition in anyamount that provides for effective autodeposition. In general, theamount can range from 1 to 50, preferably 5 to 20, and more preferably 7to 14, weight percent, based on the total amount of non-volatileingredients in the composition.

The control agent is any material that is able to improve the formationof an autodeposited coating on a metallic surface and, optionally,improve the formation of another autodeposited coating applied after thecontrol agent-containing autodeposited coating. Addition of the controlagent also increases the uniformity of the thickness of theautodeposited coating. The control agent-containing composition does notrequire an ambient staging period in order to develop fully the coating.In other words, the metallic coating conversion is complete upon dryingof the coated substrate and any subsequent coating, primer or adhesivecompositions can be applied immediately after coating and drying of thecontrol agent-containing composition. The control agent also must becompatible with the other components of the composition under acidicconditions without prematurely coagulating or destabilizing thecomposition.

The control agent may be a nitro compound, a nitroso compound, all oximecompound, a nitrate compound, or a similar material. A mixture ofcontrol agents may be used. Organic nitro compounds are the preferredcontrol agents.

The organic nitro compound is any material that includes a nitro group(—NO₂) bonded to an organic moiety. Preferably, the organic nitrocompound is water soluble or, if water insoluble, capable of beingdispersed in water. Illustrative organic nitro compounds includenitroguanidine; aromatic nitrosulfonates such as nitro ordinitrobenzenesulfonate and the salts thereof such as sodium, potassium,amine or any monovalent metal ion (particularly the sodium salt of3,5-dinitrobenzenesulfonate); Naphthol Yellow S; and picnic acid (alsoknown as trinitrophenol). Especially preferred for commercialavailability and regulatory reasons is a mixture of nitroguanidine andsodium nitrobenzenesulfonate.

The amount of control agent(s) in a multi-component composition mayvary, particularly depending upon the amount of any acid in thecomposition. Preferably, the amount is up to 20 weight %, morepreferably up to 10 weight %, and most preferably 2 to 5 weight %, basedon the total amount of non-volatile ingredients in the composition.According to a preferred embodiment, the weight ratio of nitroguanidineto sodium nitrobenzenesulfonate should range from 1:10 to 5:1.

The organic nitro compound typically is mixed into the composition inthe form of an aqueous solution or dispersion. For example,nitroguanidine is a solid at room temperature and is dissolved in waterprior to formulating into the composition.

The compositions of the invention may be prepared by any method known inthe art, but are preferably prepared by combining and milling or shakingthe ingredients and water in ball-mill, sand-mill, ceramic bead-mill,steel-bead mill, high speed media-mill or the like. It is preferred toadd each component to the mixture in a liquid form such as an aqueousdispersion.

The composition may be applied to a substrate surface by anyconventional method such as spraying, dipping, brushing, wiping,roll-coating (including reverse roll-coating) or the like, after whichthe composition typically is permitted to dry. Although conventionalapplication methods can be used, the composition can be applied viaautodeposition. The phenolic resin dispersion (A) of composition of theinvention enables autodeposition of the composition on anelectrochemically active metallic surface. Autodepositable compositionsusually are applied by dipping the metallic substrate or part into abath of the composition. The metal substrate can reside in the metaltreatment composition bath for an amount of time sufficient to deposit auniform of desired thickness. Typically, the bath residence time is fromabout 5 to about 120 seconds, preferably about 10 to about 30 seconds,and occurs at room temperature. The metal treatment composition when itis applied to the metal substrate should be sufficiently acidic to causereaction with the metal to liberate the metallic ions. Typically, the pHof the metal treatment composition should be 1 to 4, preferably 1.5 to2.5, when it is applied to the metal substrate. The compositiontypically is applied to form a dry film thickness of 1 to 15, preferably4 to 10 μm.

After simple forced air drying of a metal surface coated with thecontrol agent-containing composition the metal surface can beimmediately coated with another type of composition. The coated metalsubstrate typically is dried by subjecting it to heat and forced air.Depending upon the forced air flow, the drying usually occurs atapproximately 150-200° F. for a time period ranging from 30 seconds to10 minutes. The ambient staging period previously required after suchheated drying is no longer necessary. However, immediate subsequentcoating of the treated metal substrate is not required. Alternatively,the treated metal substrate can be stored for a period of time and thensubsequently coated with a different composition.

Although not required since a phenolic is incorporated in the metaltreatment formulation itself, the metal treatment can be used incombination with a subsequent coating of a phenolic primer as mentionedabove. The combined metal treatment and phenolic primer providescorrosion resistance comparable to phosphatizing and a conventionalphenolic primer.

Preferably, the metal treatment composition serves as a protectivecoating under a subsequently applied functional autodepositable coatingsuch as an adhesive primer or covercoat, particularly an adhesive primeror covercoat that is useful for bonding an elastomeric substrate to ametal substrate. A further advantage of the metal treatment is that itcan activate a metal surface for autodeposition of the subsequentlyapplied coating, primer or adhesive topcoat that may include a dispersedphenolic resin as described above. Such a primer is described in moredetail in co-pending, commonly assigned U.S. Provisional PatentApplication No. 60/072,779, incorporated herein by reference. Inaddition to enhancing the corrosion resistance as explained above,autodeposition activity of the subsequent coating over the controlagent-containing metal treatment composition is substantially increasedaccording to the invention.

Although preferred, the adhesive primer or covercoat applied over themetal treatment does not have to be autodepositable. Conventional,non-autodepositable primers or covercoats can be used with the metaltreatment composition. Especially useful are known elastomer-to-metaladhesive primers or covercoats such as those described in U.S. Pat. Nos.3,258,388; 3,258,389; 4,119,587; 4,167,500; 4,483,962; 5,036,122;5,093,203; 5,128,403; 5,200,455; 5,200,459; 5,268,404; 5,281,638;5,300,555; and 5,496,884. Elastomer-to-metal adhesive primers andcovercoats are commercially available from Lord Corporation.

The composition according to the invention also can be utilized byitself without any subsequent coating with an autodepositable primer oradhesive. Curing via crosslinking of the phenolic resin could occurthrough air oxidation or a surface activated chelating mechanism.

The invention will be described in more detail by way of the followingnon-limiting examples. The failure mechanism for the tested bond isexpressed in terms of percent. A high percent of rubber retained (R)onthe metal coupon is desirable since this indicates that the adhesivebond is stronger than the rubber itself. Rubber-cement failure (RC)indicates the percentage of failure at the interface between the rubberand the adhesive. Cement-metal failure (CM) indicates the percentage offailure at the interface between the metal substrate and the adhesive.

For the boiling water test the bonded test assemblies or coupons wereprepared according to ASTM-D29-B. The leading edge of each of theassemblies was stressed by suspending a two kg weight on the overlappingrubber tail and the assembly was then mounted in a fixture so that therubber tail was at an approximately 90° angle to the plane formed by thebonded interface. The stressed edge interface was exposed to boilingwater by immersing the coupon in boiling water for the indicated timeperiod. After this time, the coupons were removed from the boilingwater, allowed to cool and tested on either an Instron mechanical testerby pulling the rubber off the metal at a 45° angle stripping fixturewith a crosshead speed of 2 inches per minute or by manually peeling therubber from the metal substrate. The amount of rubber retained on thebonded area is recorded as a percentage as described above.

For the salt spray test the bonded test assemblies prepared according toASTM-D-429-B were buffed on the edges with a grinding wheel. The rubberis then tied back over the metal with stainless steel wire so as tostress the bonded area. This exposes the bond line to the environment.The assemblies then are strung on stainless steel wire and placed in asalt spray chamber. The environment inside the chamber is 100° F., 100percent relative humidity and 5 percent dissolved salt in the spray,which is dispersed throughout the chamber. The assemblies remain in thisenvironment for the indicated time period. Upon removal, the rubber ispeeled manually from the metal substrate. The amount of rubber retainedon the bonded area is recorded as a percentage as described above.

EXAMPLE 1 Preparation of Dispersed Novolak Resin

40 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt (availablefrom Andrew Chemicals), 136 g. of a water soluble resole (made fromformaldehyde and phenol, F/P ratio of 2.3, 80% solids and commerciallyavailable from Schenectady under the trade designation HRJ11722), 50 gof tert-butyl catechol and 50 g of water were mixed together and steamheated for approximately three and one-half hours until the mixturebecame very viscous. 220 g of resorcinol and 220 g of water were addedfollowed by 6 g of phosphoric acid in 20 g of water. Steam heating wascontinued for another 40 minutes. 70 g of formalin then was added whilecontinuing steam heating resulting in a concentrate. The concentrate wasfiltered and self-dispersed upon the addition of 1730 g of water.

EXAMPLE 2 Preparation of Dispersed Resole Resin

160 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt (availablefrom Andrew Chemicals), 1000 g of the HRJ 11722 water soluble resole,and 50 g of water were mixed together and steam heated for approximatelythree hours resulting in a very thick concentrate. 3600 g of water wasadded to the concentrate which then self-dispersed and was filtered.

EXAMPLE 3 Preparation of Dispersed Novolak Resin

80 g of 6,7-dihydroxy-2-naphthalenesulfonate, sodium salt (availablefrom Andrew Chemicals), 272 g of the HRJ 11722 water soluble resin, 100g of tert-butyl catechol and 50 g of water were mixed together and steamheated for approximately three and one-half hours until the mixturebecame very viscous. 440 g of resorcinol and 440 g of water were addedfollowed by 12 g of phosphoric acid in 25 g of water. Steam heating wascontinued for another 40 minutes. 130 g of formalin then was added whilecontinuing steam heating resulting in a concentrate. The concentrate wasfiltered and self-dispersed upon the addition of 3085 g of water.

EXAMPLE 4 Metal Treatment with Improved Bonding Performance

The following ingredients were mixed together in,indicated wet weightgrams to obtain a metal treatment:

Aqueous novolak dispersion of Example 1  400 g Phosphoric acid  34 gWater 3100 g

The following ingredients were mixed together in indicated wet weightgrams to obtain a coating/primer:

Carbon black  7 g ZnO  60 g Aqueous resole dispersion of Example 2 125 gPolyvinyl alcohol-stabilized resole (BKUA 2370) 200 g Dichlorobutadienehomopolymer (VERSA TL/DOWFAX 150 g stabilized) Water 300 g

The metal treatment was spray applied to one set of warm steel coupons.The treated coupons were dried at 150° F. The dried treated coupons wereheated for 10 minutes at 160° F. and the coating/primer was sprayapplied. The coupons then were heated at 150° F. for 15 minutes. Withanother set of coupons only the coating/primer was spray applied. Acommercially available aqueous adhesive covercoat (CHEMLOK®8210available from Lord Corporation) then was spray applied to the treated,primed coupons. Natural rubber was injection molded to the coupons at 1minute prebake and 5 minutes cure at 360° F. The bonded test assemblieswere subjected to the 40 hour boiling water test. The set of couponsthat were metal treated and primed exhibited a mean bonding performanceof 93R, 7CM under and the set of that were only primed exhibited a meanbonding performance of 47 R, 53 CM. When used in conjunction withCHEMLOK® 8210, the metal treatment clearly improved the bondingperformance of the coating/primer.

EXAMPLE 5 Autodepositable Metal Treatment

The following ingredients were mixed together in indicated wet weightgrams to obtain an autodepositable coating/primer:

Carbon black  21 g ZnO 180 g Aqueous resole dispersion of Example 2 400g Polyvinyl alcohol-stabilized resole (BKUA 2370) 600 gDichlorobutadiene homopolymer (VERSA TL/DOWFAX 450 g stabilized) Water1000 g 

The following ingredients were mixed together in indicated wet weightgrams to obtain a metal treatment used as an activator composition:

Aqueous novolak dispersion of Example 3 600 g Phosphoric acid 400 gWater 2700 g 

Phosphatized steel coupons were dipped in a bath of the metal treatmentcomposition (4% solids) for 5 seconds. The metal treatment compositionformed a continuous wet film on the steel coupon surface indicatingsuccessful autodeposition. The treated coupons then were dried at 150°F. The dried treated coupons were then dipped in a bath of thecoating/primer (20% solids) for 15 seconds. The coating/primercomposition formed a continuous wet film on the steel coupon surfaceindicating successful autodeposition. The coated coupons then were driedfor 15 minutes at 150° F. A one inch area then was masked off and acommercially available aqueous adhesive covercoat (CHEMLOK®8282available from Lord Corporation) was spray applied onto the treated andcoated coupons. The coupons then were prebaked for 30 seconds at 360° F.prior to bonding natural rubber for 5 minutes at 360° F. to the adhesivecoated coupon. This procedure was repeated, but the prebake was for 1minute at 340° F. and bonding was for 7 and one-half minutes at 340° F.The resulting test assemblies were subjected to the 4 hour boiling watertest and the salt spray test (500, 750 and 1000 hours). The results forall of the assemblies were 100%R bonding performance, no underbondcorrosion and very minor blistering in the unbonded portion that hadbeen masked off.

EXAMPLES 6-14 Metal Treatment that Includes Control Agent

A phenolic novolak resin aqueous dispersion was made by mixing together160 g of sodium salt of 6,7-dihydroxy-2-naphthalenesulfonate, 544 g of awater soluble resole (made from formaldehyde and phenol, F/P ratio of2.3, 80% solids and commercially available from Schenectady under thetrade designation HRJ11722), 200 g of catechol and 200 g of water andsteam heating for approximately two hours until the reaction mixturebecame very viscous and provided a clear dispersion. 880 g of resorcinoland 500 g of water were added followed by 12 g of phosphoric acid in 10g of water. Steam heating was continued for another 15 minutes. 640 g offormalin (18.5% aqueous solution) then was added while continuing steamheating resulting in a resin concentrate. The concentrate was filteredand self-dispersed upon the addition of 5900 g of water. This novolakdispersion was used to make a metal treatment composition as describedbelow.

A phenolic resole resin aqueous dispersion was made by mixing together40 g of sodium salt of 6,7-dihydroxy-2-naphthalenesulfonate, 250 g ofthe HRJ11722 resole resin, and 50 g of water and steam heating forapproximately 2 hour,s until the reaction mixture became very viscousand provided a transparent dispersion. 800 g of water was added to theresulting resin concentrate which then self-dispersed and was filtered.This resole dispersion was used to make an autodepositable primer asdescribed below.

Aqueous metal treatment compositions according to the invention wereprepared by mixing together at room temperature the followingingredients in file dry weight amounts in grams indicated in Table 1:the phenolic novolak resin aqueous dispersion described above (20%solids); aqueous solution phosphoric acid (5% solids);acrylonitrile-butadiene latex (available from B. F. Goodrich under thetradename HYCAR 1578X1, 50% solids); nitroguanidine (“NGD”)(0.6%solids); sodium nitrobenzensulfonate (“NBS”)(2.50% solids); and water.The amount of added water resulted in compositions having a total solidscontent of 6% or 8%.

TABLE 1 Ingre- Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. dient 6 7 8 9 10 1112 13 14 Phe- 49.6 49.6 49.6 47.6 47.6 47.6 44.4 44.4 44.4 nolic resinPhos- 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 phoric acid Latex23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 23.7 NGD 1.00 0.75 0.50 1.671.25 0.83 2.73 2.05 1.36 NBS 2.00 2.25 2.50 3.33 3.75 4.17 5.47 6.156.84

Steel coupons (known as Q-Panels) were dipped in baths of thecompositions at room temperature for 15 seconds (for both 6% and 8%total solids content). After immersion the treated coupons wereimmediately dried at 200° F. for 5 minutes. Immediately after drying thetreated Q-panels were dipped for approximately 15 seconds in anautodepositable primer composition. The autodepositable primercomposition was prepared by mixing together 18 g carbon black, 60 g zincoxide, 75 g mica, 360 g aqueous phenolic resole resin dispersion, 540 gphenolic resole aqueous dispersion that incorporates a non-ionicprotective colloid, presumably polyvinyl alcohol, (available fromGeorgia-Pacific under the trade designation GP 4000), 600 gdichlorobutadiene homopolymer latex and 2800 g water to form acomposition having a solids content of 15%. The treated andprimer-coated Q-panels then were dried at 200° F. and then subsequentlybaked for 15 minutes at 320° F. Autodeposited coatings had formed on allthe panels.

The resulting panels were placed in a salt spray chamber in which theenvironment inside the chamber is 95° F., 100 percent relative humidityand 5 percent dissolved salt in the spray, which is dispersed as a fogcontinuously throughout the chamber. The panels were removed from thesalt spray chamber after 300 hours and flexed on a ¼ inch mandrel. Thecrown of the flex was abraded by hand with SCOTCHBRITE abrasive cleaningpads to determine the durability of the coating that had been subjectedto the corrosive salt spray testing. The rating scale was as follows:0-massive delamination on simple flexing, extending beyond flexed area;1-delamination of flexed area only; 2-some delamination on flexing,abrasion removed remaining coating in flexed area; 3-cracking of thecoating, coating readily removed on abrasion; 4-material could beabraded off but otherwise appeared to well-adhered; 5-coating wasunaffected by flex and abrasion. The results are shown in Table 2.

TABLE 2 Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Solids content 6 7 8 9 10 1112 13 14 6% 4 4 5 4 5 5 2 1 2 6% 5 5 5 5 5 3 2 1 2 8% 5 5 4 0 2 5 0 0 0

EXAMPLES 15-17 Metal Treatment that includes Control Agent

Aqueous metal treatment compositions according to the invention wereprepared by mixing together at room temperature the ingredients in the gwet weight amounts shown below in Table 3. The aqueous phenolic resindispersion was the novolak dispersion described in connection withExamples 6-14.

TABLE 3 Ingredient Example 15 Example 16 Example 17 Phenolic resindispersion 540 540 540 Phosphoric acid 540 540 540 Water 1425 1350 1050Acrylonitrile-butadiene latex 108 108 108 (HYCAR 1578)2,4-Dinitrobenzene sulfonate 228 0 0 (5% solids) Naphthol Yellow S (5% 0300 0 solids) Picric acid (1% solids) 0 0 600

Q-panels were dipped in baths of these compositions for the amount oftime and temperature shown in Table 4 (“RT” represents room temperature)and then subjected to drying at 200° F., except for the 15 second dip ofExample 16 that was not dried. The treated panels then were immediatelydipped in a bath of the autodepositable primer composition described inExamples 6-14 for approximately 10 seconds, dried at 200° F. and thenbaked for 15 minutes at 320° F. With respect to the one sample whereinthe metal treatment was not dried, application of the primer was done ona wet surface. Autodeposited coatings had formed on each panel. Theresulting panels then were subjected to the salt spray testing for 250,500 and 750 hours. After removal from the salt spray chamber, theQ-panels were evaluated according to three tests. First, a portion ofthe panels was abraded by hand with a SCOTCHBRITE pad and the percentageamount of coating surface area that was unaffected was recorded. Second,a final portion of the panels was flexed on a {fraction (5/16)} inchmandrel and then the crown of the flex was subjected to the pencilscratch test. The results of these tests are displayed in Table 4. Withrespect to the flex test, “very poor” is massive flaking, “poor” isvisible flaking, “fair” is no flaking, but poor scratch on flexed areas.

TABLE 4 250 hr 500 hr 750 hr Abra- 250 hr Abra- 500 hr Abra- 750 hr ExDip sion Flex sion Flex sion Flex 15 10″ 100% Ex- 98% Ex- 96% Fair at RTcellent cellent 15 5″ at 100% Poor 95% Fair 99% Fair 50° C. 16 10″ 50%NA 10% NA 70% Poor at RT 17 10″ 99% Poor 100% Poor 98% Poor at RT 15 15″99% Ex- 98% Good 95% Poor at RT cellent

EXAMPLES 18-20 Metal Treatment with Various Flexibilizers

Aqueous metal treatment compositions according to the invention wereprepared by mixing together at room temperature the followingingredients in g wet weight amounts: 360 g aqueous novolak dispersiondescribed in connection with Examples 6-14; 360 g phosphoric acid; 950 gwater; 152 g dinitrobenzene sulfonate (free acid); and 72 gflexibilizer. The flexibilizer in Example 18 was a styrene-butadienerubber emulsion commercially available from Reichold Chemical Co. underthe tradename TYLAC 97924; Example 19 was a chlorosulfonatedpolyethylene latex commercially available from Lord Corporation underthe tradename HYP 605; and Example 20 was a chlorinated natural rubberlatex.

Q-panels and degreased cold-rolled steel coupons were dipped for tenseconds in the metal treatment composition (8% solids) of each Exampleand then forced air dried at 200° F. The treated Q-panels and couponsthen were immediately dipped for 10 seconds in the autodepositableprimer described above in connection with Examples 6-14. The Q-panelsand coupons then were dried for five minutes at 200° F. and then bakedfor 15 minutes at 320° F.

The resulting Q-panels were placed in the salt spray chamber for 250hours. After removal from the salt spray chamber the Q-panels wereabraded with SCOTCHBRITE pads and the percentage of coating not removedis indicated below in Table 5 under the heading “250 hrs SS”. TheQ-panels were also flexed on a {fraction (5/16)} inch mandrel. The crownof the flex was abraded by hand with SCOTCHBRITE abrasive cleaning padsto determine the durability of the coating that had been subjected tothe corrosive salt spray testing. The percentage of coating not removedacross the flexed radius is indicated below in Table 5.

A commercially available aqueous adhesive covercoat (CHEMLOK®8282available from Lord Corporation) was spray applied onto the treated andcoated coupons only. The coupons then were prebaked for 5 minutes at300° F. prior to bonding natural rubber for 16.5 minutes at 320° F. tothe adhesive coated coupon via compression molding. The bonded couponswere tested for primary adhesion performance (according to ASTM 429B) asdescribed above and the results are shown below in Table 5. The bondedcoupons also were flexed over a 1 inch mandrel, the rubber was peeledback by hand and the percentage of rubber retained on the crown of theflex is indicated in Table 5.

TABLE 5 Example No. 250 hrs SS Q-panel flex Coupon flex Adhesion 18 98%20%  95% R 100% R 19 100% 100% 100% R 100% R 20 100% 100% 100% R 100% R

EXAMPLES 21-23 Metal Treatment with Novolaks Made From DifferentModifying Agents

200 g of resorcinol, 20 g of pyrogallol, 12 g of phosphoric acid (855aqueous solution) and 220 g of water were mixed together and heated to95° C. When 95° C. was reached, 250 g of formalin (18.5% aqueoussolution) was fed to the reaction mixture over a period of 30 minutes.Steam heating was continued for another 15 minutes at which point themixture was slightly turbid and had a low viscosity (a sampleprecipitated out of solution upon dilution with water). 32 g of2-formylbenzenesulfonic acid (sodium salt, 75% moist solid) and 40 moreg of formalin then were added. After one hour and 15 minutes of steamheating the resin was very viscous. 580 g of water was added to theresin mixture and steam heating was continued until the resin wascompletely dispersible. Using essentially the same procedure5-formyl-2-furan sulfonate and I-diazo-2-naphthol-4-sulfonate stabilized(i.e., substituted for 2-formylbenzenesulfonic acid)resorcinol/pyrogallol novolak aqueous dispersions were prepared.

Three different metal treatment compositions (each containing one of thedifferent novolak dispersions) were made by mixing together thefollowing ingredients in wet weight amounts: 180 g dispersed novolakresin; 180 g phosphoric acid; 475 g water; 76 g dinitrobenzenesulfonate; and 36 g HYCAR latex. Q-panels were dipped into a bath of themetal treatment, dried for 3 minutes at 200° F, and then immediatelydipped for ten seconds into a bath of the primer composition describedin Examples 6-14. After removal from the primer bath, the Q-panels weredried at 200° F., and baked for fifteen minutes at 320° F. The resultingQ-panels had coatings varying in thickness from 0.90 to 1.06 milsindicating the formation of an autodeposited coating. The coatedQ-panels were placed in the salt spray chamber for 250 and 500 hours,respectively. The Q-panel tings were abraded with a SCOTCHBRITE pad andthe percentage of coating not moved is indicated below in Table 6.

TABLE 6 Example No. Novolak Modifying Agent 250 hr SS 500 hr SS 212-formylbenzenesulfonic acid 98% 97% 22 5-formyl-2-furan sulfonate 96%94% 23 1-diazo-2-naphthol-4-sulfonate 99% 96%

What is claimed is:
 1. An aqueous metal surface treatment compositioncomprising the following ingredients: (A) an aqueous dispersion of aphenolic novolak resin that includes a reaction product of (i) aphenolic resin precursor; (ii) an aromatic compound modifying agentwherein the modifying agent includes (a) at least one functional moietythat enables the modifying agent to react with the phenolic resinprecursor; and (b) at least one ionic moiety; and (iii) at least onemulti-hydroxy phenolic compound; and (B) an acid.
 2. An aqueouscomposition according to claim 1 wherein the ionic moiety of themodifying agent is sulfate, sulfonate, sulfinate, sulfenate oroxysulfonate and the dispersed phenolic novolak has a carbon/sulfur atomratio of 20:1 to 200:1.
 3. An aqueous composition according to claim 1wherein the phenolic resin precursor comprises a resole.
 4. An aqueouscomposition according to claim 1 wherein the modifying agent is selectedfrom a sulfonated naphthalene, a sulfonated formyl group-containingcompound or a sulfonated diazo compound.
 5. An aqueous compositionaccording to claim 1 wherein the reaction-enabling moiety is selectedfrom hydroxy, hydroxyalkyl, formyl or diazo.
 6. An aqueous compositionaccording to claim 1 wherein the modifying agent comprises a structurerepresented by formula Ia or Ib:

wherein X is the ionic moiety; Y is the reaction-enabling moiety; Z is achelating substituent; L¹ is a divalent linking group; a is 1; b is 1 to4; m is 0 or 1; and c and d are each independently 0 to 3, providedthere are not more than 4 substituents on each aromatic ring.
 7. Anaqueous composition according to claim 1 wherein the ionic moiety is asulfonate and the reaction-enabling moiety is selected from hydroxy orhydroxyalkyl.
 8. An aqueous composition according to claim 1 wherein themodifying agent comprises dihydroxy naphthalenesulfonate.
 9. An aqueouscomposition according to claim 8 wherein the phendic resin precursorcomprises a resole.
 10. An aqueous composition according to claim 9wherein the multi-hydroxy phenolic compound is selected from resorcinolor pyrocatechol.
 11. An aqueous composition according to claim 1 whereinthe multi-hydroxy compound is selected from resorcinol, pyrocatechol,hydroquinone, pyrogallol, 1,3,5-benzenetriol and tert-butyl catechol.12. An aqueous composition according to claim 1 wherein the acidcomprises phosphoric acid.
 13. An aqueous composition according to claim10 wherein the acid comprises phosphoric acid.
 14. An aqueouscomposition according to claim 1 wherein the pH of the composition is 1to
 4. 15. An aqueous composition according to claim 1 further comprisinga flexibilizer ingredient.
 16. An aqueous composition according to claim15 wherein the flexibilizer is selected from (poly)butadiene, neoprene,styrene-butadiene rubber, nitrile rubber, halogenated polyolefin,acrylic polymer, urethane polymer, ethylene-propylene copolymer rubber,ethylene-propylene-diene terpolymer rubber, styrene-acrylic copolymer,polyamide and poly(vinyl acetate).
 17. An aqueous composition accordingto claim 16 wherein the flexibilizer is selected from halogenatedpolyolefin, nitrile rubber and styrene-acrylic copolymer.
 18. An aqueouscomposition according to claim 13 further comprising a flexibilizeringredient selected from halogenated polyolefin, nitrile rubber andstyrene-acrylic copolymer.
 19. An aqueous composition according to claim1 wherein the composition is autodepositable on the metal surface. 20.An aqueous composition according to claim 1, wherein the dispersednovolak comprises a structure represented by:

wherein X is the ionic moiety; Y is the reaction-enabling moiety; a is 0or 1; n is 0 to 5 and R4 is independently hydroxyl, alkyl; aryl;alkylaryl; or aryl ether.
 21. An aqueous metal surface treatmentcomposition formed by combining: (A) an aqueous dispersion of a phenolicnovolak resin that includes a reaction product of (i) a phenolic resinprecursor; (ii) an aromatic compound modifying agent wherein themodifying agent includes (a) at least one functional moiety that enablesthe modifying agent to react with the phenolic resin precursor; and (b)at least one ionic moiety; and (iii) at least one multi-hydroxy phenoliccompound; and (B) an acid.
 22. A method for providing a protectivecoating on a metallic surface comprising applying the aqueous metalsurfaces treatment composition according to claim 1 to the surface. 23.A method according to claim 22 wherein the metallic surface is dippedinto a bath of the composition so that the composition autodeposits theprotective coating on the metal surface.
 24. A method according to claim22 wherein the modifying agent is selected from a sulfonatednaphthalene, a sulfonated formyl group-containing aromatic compound or asulfonated diazo aromatic compound.
 25. A method according to claim 22wherein the modifying agent comprises dihydroxy naphthalenesulfonate,the phenolic resin precursor comprises a resole, and the multi-hydroxyphenolic compound is selected from resorcinol or pyrocatechol.
 26. Amethod according to claim 22 wherein the acid comprises phosphoric acid.27. A method according to claim 25 wherein the acid comprises phosphoricacid.
 28. A method according to claim 22 wherein the composition furthercomprises a flexibilizer ingredient.
 29. A method according to claim 28wherein the flexibilizer ingredient is selected from halogenatedpolyolefin, nitrile rubber and styrene-acrylic copolymer.
 30. An aqueouscomposition according to claim 1, wherein the solids content is in therange of 1 to 10%.
 31. An aqueous composition according to claim 1,wherein the composition is substantially free of volatile organiccomponents.
 32. A method according to claim 27 wherein the compositionfurther comprises a flexibilizer ingredient selected from halogenatedpolyolefin, nitrile rubber and styrene-acrylic copolymer.
 33. An aqueousautodeposition composition comprising the following ingredients: water;acid in an amount sufficient to react with a metal surface being treatedto generate multivalent ions; an acid stable autodepositable componentmodified to contain ionic groups; and at least one organic nitrocompound.
 34. A composition according to claim 33 wherein the organicnitro compound is selected from nitroguanidine, aromatic nitrosulfonate,Naphthol Yellow S or picnic acid.
 35. An aqueous autodepositioncomposition comprising the following ingredients: water; acid; anautodepositable component; and an organic nitro compound comprisingnitroguanidine and an aromatic nitrosulfonate.
 36. A compositionaccording to claim 35 wherein the aromatic nitrosulfonate comprises anitro or dinitro benzenesulfonate.
 37. A method for providing aprotective coating on a metallic surface comprising applying the aqueousautodeposition composition according to claim 33 to the surface.
 38. Anaqueous autodeposition composition comprising the following ingredients:water; acid in an amount sufficient to react with a metal surface beingtreated to generate multivalent ions in an amount sufficient forautodeposition; a phenolic resin that is the reaction product of aphenolic compound with an aldehyde compound; and at least one controlagent selected from a nitro compound, a nitroso compound, an oximecompound and a nitrate compound.
 39. A composition according to claim 38wherein the phenolic resin comprises an aqueous dispersion of a phenolicnovolak resin that includes a reaction product of (i) a phenolic resinprecursor; (ii) a modifying agent wherein the modifying agent includes(a) at least one functional moiety that enables the modifying agent toreact with the phenolic resin precursor; and (b) at least one ionicmoiety; and (iii) at least one multi-hydroxy phenolic compound.
 40. Acomposition according to claim 39 wherein the control agent comprises anorganic nitro compound.
 41. A composition according to claim 38 whereinnitroguanidine and an aromatic nitrosulfonate are control agents.
 42. Acomposition according to claim 41 wherein the aromatic nitrosulfonatecomprises a nitro or dinitro benzenesulfonate.
 43. A compositionaccording to claim 38 further comprising a phosphoric acid ingredient.44. A composition according to claim 38 further comprising aflexibilizer ingredient.
 45. A composition according to claim 44 whereinthe flexibilizer ingredient is selected from halogenated polyolefin,nitrile rubber and styrene-acrylic copolymer.
 46. A compositionaccording to claim 38 wherein the control agent is, present in an amountof up to 20% by weight based on the total weight of non-volatileingredients in the composition.
 47. A composition according to claim 38wherein the modifying agent is selected from a sulfonated naphthalene, asulfonated formyl group-containing compound or a sulfonated diazocompound.
 48. A composition according to claim 47 wherein the modifyingagent comprises a dihydroxy naphthalenesulfonate.
 49. A compositionaccording to claim 48 wherein the phenolic resin precursor comprises aresole, the multi-hydroxy phenolic compound is selected from resorcinol,pyrocatechol, hydroquinone, pyrogallol, 1,3,5-benzenetriol or tert-butylcatechol, the control agent comprises an organic nitro compound andfurther comprising phosphoric acid and a flexibilizer.
 50. An aqueousautodeposition composition formed by combining: a) an aqueous dispersionthat includes a phenolic resin that is the reaction product of aphenolic compound with an aldehyde compound; and b) at least one controlagent selected from a nitro compound, a nitroso compound, an oximecompound and a nitrate compound water; and c) acid in an amountsufficient to react with a metal surface being treated to generatemultivalent ions in an amount sufficient for autodeposition.
 51. Amethod for providing a protective coating on a metallic surfacecomprising applying the aqueous autodeposition composition according toclaim 38 to the surface.
 52. A method according to claim 51 wherein themetallic surface is dipped into a bath of the composition so that thecomposition autodeposits the protective coating on the metal surface.53. A method according to claim 51 further comprising a subsequent stepof applying a second autodeposition composition.
 54. A method accordingto claim 51 further comprising a subsequent step of applying an adhesiveprimer or adhesive covercoat.
 55. A method according to claim 51 whereinthe control agent comprises an organic nitro compound.
 56. A methodaccording to claim 51 wherein nitroguanidine and an aromaticnitrosulfonate are the control agents.
 57. A method according to claim56 wherein the aromatic nitrosulfonate comprises a nitro or dinitrobenzenesulfonate.
 58. A method according to claim 51 wherein thecomposition further comprises a phosphoric acid ingredient.
 59. A methodaccording to claim 51 wherein the composition further comprises aflexibilizer ingredient.
 60. A method according to claim 59 wherein theflexibilizer ingredient is selected from halogenated polyolefin, nitrilerubber and styrene-acrylic copolymer.
 61. A method according to claim 51wherein the control agent is present in an amount of up to 20% by weightbased on the total weight of non-volatile ingredients in thecomposition.
 62. A method according to claim 51 wherein the modifyingagent is selected from a sulfonated naphthalene, a sulfonated formylgroup-containing compound or a sulfonated diazo compound.
 63. A methodaccording to claim 62 wherein the modifying agent comprises a dihydroxynaphthalenesulfonate.
 64. A method according to claim 63 wherein thephenolic resin precursor comprises a resole, the multi-hydroxy phenoliccompound is selected from resorcinol, pyrocatechol, hydroquinone,pyrogallol, 1,3,5-benzenetriol or tert-butyl catechol, the control agentcomprises an organic nitro compound and further comprising phosphoricacid and a flexibilizer.
 65. An aqueous metal surface treatmentcomprising the following ingredient: an aqueous dispersion of asulfur-modified phenolic resin; and an acid in an amount sufficient toreact with a metal surface being treated to generate multivalent ions inan amount sufficient for autodeposition.
 66. The aqueous metal surfacetreatment according to claim 65 wherein the sulfur-modified phenolicresin comprises a sulfonate-modified phenolic resin.
 67. An aqueousautodeposition composition comprising the following ingredients: anautodepositable sulfur-modified novolak resin; and an acid in an amountsufficient to react with a metal surface being treated to generatemultivalent ions in an amount sufficient for autodeposition.
 68. Anautodeposition composition according to claim 67 wherein the acidcomprises phosphoric acid.
 69. A method for providing a protectivecoating on a metallic surface comprising applying the aqueous metalsurface treatment composition according to claim 65 to the surface. 70.A method according to claim 69 wherein the metallic surface is dippedinto a bath of the composition so that the composition autodeposits aprotective coating on the metal surface.
 71. A method for providing aprotective coating on a metallic surface comprising applying the aqueousautodeposition composition according to claim 67 to the surface.
 72. Amethod for protecting the metallic surface comprising applying anaqueous autodeposition composition according to claim 67, to a metallicsurface wherein the metal of this surface is iron, zinc or steel.